EP 1 819 382 B1 describes an injection device comprising a housing, a dose setting member, a torsion spring connected to the dose setting member in such a way that energy is accumulated in the torsion spring upon rotation of the dose setting member, and a rotatably mounted display member, which is threadedly engaged with the housing, coupled with the dose setting member and provided to display the dose set. A drive member is coupled with the dose setting member via a unidirectional ratchet. Upon release of a locking member, the torsion spring rotates the drive member, and the drive member rotates a piston rod, which is helically advanced by a threaded engagement with the housing. The dose setting member is axially retractable, and the dose set can be reset or reduced when the dose setting member is pulled to disengage the ratchet.
WO 2010/020311 A1 describes an injection device comprising a housing with a first window provided with a first lens, and an inner sleeve with a second window provided with a second lens, which slides axially within the first window to display numbers indicating the size of a selected dose. The numbers are helically arranged on an axially locked rotatable dial sleeve, which is arranged inside the inner sleeve and is threadedly engaged with the inner sleeve. The rotation of the dial sleeve is synchronized with the displacement of the second window. The lens in the first window distorts the display, and the lens in the second window compensates for the distortion to increase the legibility of the number viewed through both windows.
US 2010/0168677 A1 discloses a drive mechanism of an injection device comprising a housing part, a piston rod, a tube displaying numbers, and an injection sleeve rotationally locked to the housing part and threadedly engaged with the outer surface of the tube. A releasable coupling between a rotary knob and the injection sleeve is effective during injection and prevents the rotary knob from being rotated. A further releasable coupling between the rotary knob and a driver, which is rotationally locked and axially movable relative to the tube, is effective during dose setting and transfers a rotation of the rotary knob into a rotation of the tube, which causes an axial shift of the injection sleeve. A window of the injection sleeve, which displays an area of the surface of the tube and the numbers located in this area, is guided in a window of the housing part during the axial displacement of the injection sleeve.
WO 2011/060785 A1 discloses a drive mechanism of an injection device comprising a housing, a piston rod and a driver, which is rotationally locked to a scale drum displaying the amount of the dose set. A dose selector is releasably rotationally coupled to the driver. When the dose selector is rotated to set a dose, the scale drum and the driver are screwed out of the housing. For injection, the dose selector is pushed to release the coupling with the driver, and the scale drum, the driver and the piston rod are collectively advanced. A sliding window is axially movable in an elongated hole in the housing and has a thread segment, which engages a thread on the outer surface of the scale drum.
WO 2011/036134 A2 discloses an assembly and indicator for a drug delivery device, which comprises a first detent configured to releasably secure the indicator in a first indication position such that movement into a second indication position is allowed, and a second detent configured to secure the indicator in the second indication position such that movement into the first indication position is prevented.